The disclosure relates to removing hydrocarbons from the evaporative emissions of a motor vehicle, more particularly, to the seals employed within a hydrocarbon scrubber used in treating evaporative emissions from a motor vehicle fuel tank.
The fuel tank of a motor vehicle is a potential source of evaporative emissions of hydrocarbons. Evaporative emissions result from vaporization of fuel due to diurnal changes in ambient pressure and/or temperature, and the escape of fuel vapors during refueling of the vehicle. The venting of fuel vapor from the fuel tank due to diurnal pressure and/or temperature changes (i.e., diurnal emissions) is responsible for a majority of motor vehicle evaporative emissions. Diurnal emissions result when air flows into the fuel tank as a result of changes in environmental pressure and/or temperature. Once inside the fuel tank, the air becomes saturated with fuel vapor. Changes that result in a higher pressure within the fuel tank cause this air saturated with fuel vapor to flow back to the atmosphere. As the ambient pressure and temperature change, the process repeats. The net effect is the undesirable release of raw hydrocarbons into the atmosphere.
To limit or eliminate the occurrence of evaporative emissions, the air flow out of the fuel tank is treated to remove the hydrocarbons and other contaminants with a hydrocarbon scrubber. A hydrocarbon scrubber includes a sorbent material (i.e., adsorbent, absorbent, or both), disposed in fluid communication with the fuel tank and the atmosphere through a system of conduits and valves.
The sorbent material employed in the hydrocarbon scrubber, which often takes the form of a monolith, comprises a sorbent formed into a rigid or semi-rigid embodiment disposed within an evaporative canister, also known as a shell. The shell is connected to the conduits and valves, thereby providing fluid communication from the fuel tank to the atmosphere through the sorbent monolith. Efficient and effective removal of hydrocarbons by the hydrocarbon scrubber can be accomplished when the sorbent monolith sealably engages the shell. However, effective sealing of a sorbent monolith in a hydrocarbon scrubber remains an area in need of improvement.
The need for improvement in providing a sorbent monolith seal is the result of several factors inherent to the scrubber system. To remove hydrocarbons, the sorbent should possess a large surface area. To provide the needed surface area, sorbent monoliths typically comprise thin walled channels, which render the sorbent monolith fragile and prone to physical destruction upon application of force or vibration. Utilization in a moving vehicle, typically subjects the sorbent monolith to significant amounts of vibration and other motions incompatible with the thin-walled design. Other factors particular to a motor vehicle applications include the temperature extremes a sorbent monolith and surrounding system are routinely subjected to, including both contraction upon cooling, and expansion upon heating, as well as the sustained extremes encountered under normal operational conditions (e.g., temperatures ranging from about xe2x88x9240xc2x0 C. to about 200xc2x0 C.). Thus, if the hydrocarbon scrubber system is to be durable and function efficiently, the sorbent monolith should be sealed and protected within the shell.
Sorbent monolith seals include sponge rings and various types of rubber O-rings. However, upon insertion of a sorbent monolith into the shell, the seals often xe2x80x9croll-offxe2x80x9d the end and thus do not adequately seal or provide protection of the monolith within the shell.
When seals are utilized that are of a size so as to provide the necessary seal and prevent roll-off, greater insertion force is required. This greater insertion force can necessitate the application of an exterior lubrication to the outer housing or seals prior to sorbent monolith insertion. The application of exterior lubrication adds undesirable cost and complexity to the hydrocarbon scrubber.
Disclosed herein is a hydrocarbon scrubber and a method for use thereof. The hydrocarbon scrubber comprises: a monolith; a seal disposed concentrically around an end of the monolith, wherein the seal comprises an inner surface having a diameter equal to or less than an outer diameter of the monolith, a shoulder member protruding from the seal and physically contacting at least a portion of an end face of the monolith, and a rib member disposed on an outer side of the seal and in physical contact with the shell.
The method for using a hydrocarbon scrubber, comprises: introducing a fuel gas to a monolith first end of a monolith, removing hydrocarbons from the introduced gas to produce a clean gas, exhausting the clean gas through a second end of the monolith, introducing atmospheric gas through the second end of the monolith to remove the hydrocarbons from the monolith, wherein the a seal is disposed concentrically around an end of the monolith.
The above described and other features are exemplified by the following figures and detailed description.